Two-position switch



.iuly 1, 1947- M. L. GLOGAU TWO POSITION swucn 2 Sheets-Sheet 1 Filed lay 6. 1944 Patented July 1, 1947 2,423,381 7 TWO-POSITION SWITCH Manfred L. Glogau,

Allen-Bradley Company,

Shorewood, Wis., assignor to Milwaukee, Wis., a

corporation of Wisconsin Application May 6, 1944, Serial No.

Claims. (Cl. 200-67) This invention relates to over center or snap action switches of the high precision type one example of which is described and shown in Patent No. 2,260,964 of Gustav O, Wilmsissued October 28, 1941,.and resides in an improvement therein in which the advantages of a switch of this type in its unsymmetrical single position form is made available in a two position form thereof.

The apparatus of this invention has distinct advantages of compactness which permit it to be mounted without providing for. actuating means passing through a surface updn which the switch is mounted and at the same time without increasing the width of the switch to provide for actuating means passing through or around the operating parts thereof. The apparatus furthermore has the advantage that it permits the manufacture of a standardized switch, the main part of which may be employed without modification to form either a single position, self-returning type of switch or one which is adapted to be selfretaining in two positions. As an additional manufacturing advantage the apparatus of this invention dispenses with the necessity for lost motion actuators of high precision, the manufacture and assembly of which has proven difficult and expensive.

the type of Patent No. 2,260,964 have among other advantages the inherent property of an invariable actuation point at which snap over occurs. For example when used as a limit switch for a feed mechanism of a machine tool, the parts can be repeatedly arrested or reversed at the same position within limits required for high precision work, or in the case of a pressure switch where a fluid actuated diaphragm moving against a calibrated spring actuates the switch by its movement, the pressure at which the switch passes the actuating point will repeatedly fall within limits which are a small percent of the total pressure change. This property of precision may be impaired by an accumulation amounts of foreign matter parts in the actuating mechanism. parts stand separated for long intervals they may acquire an accidental coating of foreign matter and consequently may re-engage at times with a markedly altered position response. Because of this a single position or self returning switch in which the actuating parts remain in engagement at all times is less affected by a dusty environment and continues to respond desired to a greater degree at the precise position than the two position form-of such switches which have all required lost motion actuators one part of which is disengaged at all times.

of stationary switch contacts of this invention to produce a switch having the ability to hold a precise position response calibration, and at the same time one which will be self retaining in two positions. A two-position switch is provided by the apparatus of this invention while at the same time all of the actuating parts are maintained in engagement with one-another continuously. In this way not only is there largely eliminated the possibility of accumulation of foreign matter between adjacent actuating parts which would impair the precisionof position response but abrasive wear due to intervening foreign matter is avoided to a considerable degree and dimensional changes resulting from permanent deformation induced by impact which otherwise occurs in a lost motion actuating mechanism of a snap-over type of switch is minimized.

This invention is herein described by reference to the accompanying drawings forming a Part hereof and in which there is set forth by way of illustration and not of limitation one form in which the invention may be embodied. In these drawings:

Fig. 1 is a front view in elevation of one form of the switch of this invention;

Fig. 2 is a side view in elevation of the switch shown in Fig. 1;

Fig. 3 is a rear view in elevation of the switch shown in Fi 1;

Fig. 4 is a side sectional view in elevation as viewed through the plane 4--4 indicated in Fig. 1, showing the parts in one of the two self retaining positions;

Fig. 5 is a similar side sectional view in elevation as viewed through the plane 4-4 indicated in Fig. 1, showing the parts in the other one of the two self-retaining positions; and

Fig. 6 is a detail side sectional view in elevation of the contact carrier and throwing spring of the switch of Fig. 1 in unstressed condition.

Referring now to the several views of the drawings, the switch is shOWn assembled upon a molded insulating mounting designated generally by the numeral The mounting l is of a generally trough-like configuration with the upper open end of the trough flanked by shelves 2 and 3 which serve respectively for the support 4 and 5. The lower end of the trough-like mounting l is crossed by a ledge 6, which furnishes an anchorage for a re- It is an object silient movable contact carrier '8 carrying a movengagement with pointed tips formed as shown The expansion spring acting against the members 1 on the spring 8, and the carrier 1.

and 8 tends to hold them or to help to hold them, as an overcenter means in either of the positions shown in Figs. 4 and 5, once said members have been brought to said positions in a 'manner to be described more fully hereinafter.

Serving as a limit to the travel of the flat throwing sprin 8 when in the position shown in Fig. 4, is the stop I 2 in the form of an integral lug extending from the terminal plate 9. In similar fashion a small projection l3, rising from the floor of the trough-like mounting l, acts as a stop when the parts are in the position shown inFig. 5. i Q

As clearly appears in Fig. 6, the integral assembly of carrier 1, and fiat throwing spring 8, is so formed that the throwing spring 8 bends away from the contact carrier 1 by-an appreciable amount when these parts are subject to no stress, with the result that the spring 8 and H, and the carrier 1, when assembled, tend without external force applied thereto, to assume and if displaced to return to the position of the parts shown in Fig, 5. The material of the throwing spring 8, near its anchored end, therefore constitutes means for resiliently biasing the parts in the manner described. The nature of this part of the apparatus of this invention as to its structure and function is as fully disclosed in Wilms Patent No. 2,260,964, above referred to.

In accordance with the present invention, however, for the purpose of actuating the switch parts above described, that is to say, for moving the same from the position shown in Fig. 5, to the position shown in Fig. 4, and for permitting return of the same and for holding the parts in either of said positions,- an actuator assembly secured to and extending through the rear of the mounting I, is provided. This actuator assembly includes a thrust member I4, composed of molded insulatin material having hard metallic inserts and I8 molded in place to form wearing ends therefor. The thrust member I4 is mounted upon and guided in its limited movement by a thin metallic strap H in the form of a capital T, secured in place upon a metallic actuator base I8, by rivets H, which pass through the base 8 and the mounting to secure the whole together as appears in Figs. 1, 2, and 3. An additional rivet aids in providing the necessary rigidity of attachment of the base l8 to the mountin I.

Also forming a part of the actuator assembly is a rocker arm 2|, one end of which engages the wearing end I6 of the thrust member I4,

and the other end of which is provided with a. spring seat 22. The rocking or pivotal mounting for the rocker arm 2|, is provided by pivotal engagement of inwardly bent ears 24, formed as a part of the rocker 2| with a pivot pin 25. The pivot pin is secured as shown in outwardly bent ear 28, which are formed as a part of the base plate l8. A counter-loading or resilient Jneans in the form of preloaded low rate expansion spring 23 is interposed between the strap l1 (backed up by the base l8) and the seat 22 on the rocker arm 2|, so as to tend to force the lower end of the rocker end l6 of the thrust member In this way there is provided two opposing tendencies, that is to say, the net tendency of the throwing spring 8 to return to the position shown in Fig. 5 over and above the modifying ,action of spring H, on the one hand, and the tendency of the thrust member H to move in the opposite direction under influence of the spring 23, on theother hand. In accordance with this inventio'nlthese tendencies are balanced or related to one'anotherin magnitude so that the returning tendency of the throwing spring 8, in the position shown in Fig. 4, less the opposing action of the spring H, in that position is exceeded by the opposing action of spring 23. By way of illustrative example, applicable of course only to one specific physical embodiment; it the transverse component at the level of actuator I4, due to spring II is 1% pound in either position and the returning tendency of spring 8, in the position shown in Fig. 4 is 1 pound, a net returning tendency of pound will prevail. If in opposition to this, the spring 23 exerts at the level of the actuator l4, a force of 1% pound, the switch will be SelLretaining in the position shown in Fig. 4. Furthermore, the force required to throw the switch from this position when applied to the rocker 2|, at the same radius as that of the actuator II, will be 1% minus 1 6 or 1% pound.

With the switch in the position shown in Fig. 5

the spring II and to a smaller'extent the spring 8 both oppose a throwing action to the extent of 1%; pound for the spring II, and let us sayfio pound for the spring 8, or a total of one pound. Opposing this is the action of spring 23 acting through rocker 2| with an efiective transverse component at the level of the actuator H of 1% pound, or very little more. The switch, therefore, is self retaining in this position also. In this case th force required to be applied to the rocker at equivalent radius to throw the switch is 1 pound minus 1% p und, or 1 6 pound. The switch, therefore, is self retaining in two positions with substantially the same amount of force being required to throw the switch from either position. By making the spring 23 weaker or stronger, within limits, the two position characteristic of the switch may nevertheless be preserved, but a greater force will be required to throw the switch from one of the positions than from the other. In other words in the absence of,the counterloading spring 23, the snap switch itself has a net returning tendency in the remote position of pound, while in the near position this net returning tendency increases to 1 pound. The permanently connected counter-loading spring 23, however, is proportioned to these properties so as to apply a force which exceeds the 1% pound returning tendency in the remote position but which is less than the pound returning tendency in the near position. With the forces involved related in this manner a structure results which is self-retaining in both near and remote positions and which moves with a snap action in moving to and from said positions.

For engagement with a mechanism to actuate the switch, an arm 21 is secured to the rocker 2| by rivets as shown.

arm 2| against the placed therefrom to said carrier and said throwing member The maintenance at all times of the rocker 2| in contact with the end If; of the thrust member l4 and the maintenance of the end [5 of thrust member M in contactwith the spring 8 is a matter of importance. These parts remaining at all times in contact exclude any accidental coating of-foreign matter which might otherwise cause the switch to have an altering position response. This is in contrast with other two position switches wherein the actuator mechanism includes parts which disengage when the snap over action occurs. If such a switch is idle for long intervals in a dusty environment the disengaged parts upon re-engagement will not come to the same precise relationship to one another and if the switch is of the precision type the calibration will be lost. This difliculty is not encountered in the switch of this invention in which the actuating parts are at all times in engagement. It is intended that the protection to be afforded hereby extend to the full limit of the inventive advance herein disclosed as defined by the claims hereto appended. Y r

I claim:

1. In a two position snap over switch, a movable contact. carrier, a movable throwing member, said carrier and said throwing member being capable of passing to and from positions on opposite sides-of one another and being resiliently related to one another to assume and when distend to return to one pf said positions in the absence of applied stress, over center means interposed between said carrier and said throwing member adapted to urge them toward either of said positions but incapable of sufficient force to prevent return of said carrier and throwing member to said position to which they tend to return, an actuator adapted to engage said throwing member, a counter-loading means adapted to act upon said actuator to cause it to maintain engagement with said throwing member at all times and to exert a force in such a direction and with such intensity as to cause aided by said over center means when in said position from which they tend to return to remain there, the intensity of the force exerted by said counterloading means being insufficient when said carrier and throwing member are in said position to which they tend to return to overcome the opposition of said over center means, a movable electrical contact and means for establishing electrical connection therewith carried upon said contact carrier, a stationary electrical contact disposed to be engaged by said movable contact when said carrier is in one of its positions, and means for applying an actuating force to said actuator.

2. In a two position snap over switch, a resilient contact carrier rigidly mounted at one end, a fiat throwing spring, said carrier and said throwing spring having free ends capable of passing to and from positions on opposite sides of one another and being formed to assume and when displaced therefrom to tend to return to one of said positions in the absence of applied stress, an expansion spring interposed between the free ends of said carrier and said throwing spring adapted to urge said free ends toward separation when in either of said positions but incapable of sufficient expansive force to prevent return of said carrier and throwing spring to that position to which they tend to return, an actuator adapted to engage said throwing spring, counter-loading resilient means adapted to act upon said actuator to cause it to maintain engagement with said throwingspring at all times and to exert a force in such a direction and with such intensity as to cause said carrier and said throwing spring aided by saidexpansion spring to remain in that position from which they tend to return, the intensity; of the force exerted by said counter-loading resilient means being insufiicient when said carrier and throwing spring are in said position to which they tend to return to overcome the opposition of said expansion spring, a movable electrical contactand means for establishing electrical connection therewith carried upon said contact carrier, a stationary electrical contact disposed to be engaged by said movable contact when said carrier is in one of its posltions, and means for applying an actuating force to said actuator.

3. In a two position snap over switch, a resilient flat-leaf movable contact carrier rigidly mounted at one end, a flat throwing spring mounted at one end close to the mounting of said contact carrier, said carrier and said throwing spring in unstressed normal position being formed to be non-coplanar at the free ends thereof remote from their mountings, said free ends being capable by reason of resilient deflection of passing from their lower stress normal position to a higher stress position on opposite sides of one another and of returning therefrom, an expansion spring interposed between the free ends of said carrier and said throwing spring adapted to urge said free ends toward separation when in either of said positions but incapable of sufficient expansive force to retain said carrier and throwin spring in said higher stress position, an actuator adapted to engage said throwing spring at a point close to its mounting, resilient means adapted to act upon said actuator to cause it to maintain engagement with said throwing spring at all times and to exert a force in such a direction and with such intensity as to cause said carrier and said throwing spring aided by said expansion spring when in said higher stress position to remain there, the intensity of the force exerted by said resilient means being insufficient when said carrier and throwing spring are in said lower stress position to overcome the opposition of said expansion spring, a movable electrical contact and means for establishing electrical connection therewith carried upon said contact carrier, a stationary electrical contact disposed to be engaged by said movable contact when said carrier is in one of its positions, and means for applying an actuating force to said actuator.

4. In a two position snap over switch, a resilient bifurcated flat-leaf movable contact carrier rigidly mounted at one end, a shorter fiat throwing spring within the crotch of said carrier and integrally joined thereto at said mounting, said carrier and said throwing spring in unstressed normal position being formed to be non-coplanar at the ends thereof remote from said mounting, said remote ends being capable by reason of resilient deflection of passing from their lower stress normal position to a higher stress position on opposite sides of one another and of returning therefrom, an expansion spring interposed between the free end of said throwing spring and the crotch of said carrier adapted to urge said free end and said crotch toward separation when in either of said positions but incapable of sufiicient expansive force to retain said carrier and throwing spring in said higher stress position, an actuator adapted to engage said throwing spring at a point close to its mounting,

resilient means adapted to act upon said actuator to cause it to maintain engagement with said throwing spring at all times and to exert a force in such a direction and with such intensity as to cause said carrier and said throwing spring aided by said expansion spring when in said higher stress position to remain there, the intensity of the force exerted by said resilient means being insufficient when said carrier and throwing spring are in said lower stress position to overcome the opposition 01' said expansion spring, a movable electrical contact and means for establishing electrical connection therewith carried upon said contact carrier, a stationary electrical contact disposed to be engaged by said movable contact when said carrier is in one of its positions, and means Ior applying an actuating force to said actuator.

54 In a circuit controlling apparatus a snap switch capable of occupying a remote and a near position and of passing with forward and return movements from one to another with a snap action and adapted to remain in and return to said near position with an increasing returning tendency in the absence of applied force, a permanently connected counter-loading means cooperatively engaging said snap switch and adapted to apply thereto a counter-loading force in opposition to said returning tendency of an intensity exceeding said returning tendency when said snap switch is in said remote position but of intensity less thanthe increased returning tendency of said snap switch when in said near position, and means for applying actuating force adapted to receive externally applied oppositely directed forces and to apply the same to diminish said counter-loading force when said snap switch is in the remote position to the point where return movement of said snap switch will take place and to augment said counter-loading force when said snap switch is in the near position to the point where forward movement of said snap switch will take place whereby said snap switch is rendered self-retaining in both remote and near positions.

MANFRED L. GLOGAU.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,236,680 Fry Apr. 1, 1941 2,260,964 Wilms Oct. 28, 1941 2,289,108 Eaton July 7, 1942 

